Brief title for your desired feature: Lock horizontal and vertical while pressing a hotkey
How would you like the feature to work? in schematic and PCB layout mode holding CNTL and dragging a piece would lock the movement into a vertical OR horizontal only movement. Basically force moving in a straight line.
Why is this feature important to you? Sometimes you don't want to move freely or by the grid. You just want to move precisely to the left or down or whatever